user service: add oauth and profile images (#17784)

* users: add cache to service

* reflect review comments

* add oauth

* move profile picture genaration

* reflect review comments

* move default bot image to users package

* add missing wraps and apply suggestions

* add comment for app.GetSession

services/users/errors.go

@@ -6,9 +6,20 @@ package users
 import "errors"
 
 var (
-	AcceptedDomainError = errors.New("the email provided does not belong to an accepted domain")
-	VerifyUserError     = errors.New("could not update verify email field")
-	UserCountError      = errors.New("could not get the total number of the users.")
+	AcceptedDomainError       = errors.New("the email provided does not belong to an accepted domain")
+	VerifyUserError           = errors.New("could not update verify email field")
+	UserCountError            = errors.New("could not get the total number of the users.")
+	UserCreationDisabledError = errors.New("user creation is not allowed")
+
+	GetTokenError            = errors.New("could not get token")
+	GetSessionError          = errors.New("could not get session")
+	DeleteTokenError         = errors.New("could not delete token")
+	DeleteSessionError       = errors.New("could not delete session")
+	DeleteAllAccessDataError = errors.New("could not delete all access data")
+
+	DefaultFontError   = errors.New("could not get default font")
+	UserInitialsError  = errors.New("could not get user initials")
+	ImageEncodingError = errors.New("could not encode image")
 )
 
 // ErrInvalidPassword indicates an error against the password settings